java工具类

import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.util.Calendar;
import java.util.Date;

public class Main {
    public static void main(String[] args) {
        System.out.println(format(LocalDateTime.now().minusDays(1)));
        System.out.println(format(LocalDateTime.now().minusSeconds(2)));
        System.out.println(format(LocalDateTime.now().minusWeeks(5)));
    }

    private static final long ONE_MILLISECOND = 1000L;
    private static final long ONE_MINUTE = 60000L;
    private static final long ONE_HOUR = 3600000L;
    private static final long ONE_DAY = 86400000L;

    private static final String ONE_SECOND_AGO = "秒前";
    private static final String ONE_MINUTE_AGO = "分钟前";
    private static final String ONE_HOUR_AGO = "小时前";
    private static final String ONE_DAY_AGO = "天前";
    private static final String ONE_MONTH_AGO = "1个月前";
    private static final String TWO_MONTH_AGO = "2个月前";
    private static final String THREE_MONTH_AGO = "3个月前";
    private static final String FOUR_MONTH_AGO = "4个月前";
    private static final String FIVE_MONTH_AGO = "5个月前";
    private static final String SIX_MONTH_AGO = "6个月前";
    private static final String SEVEN_MONTH_AGO = "7个月前";
    private static final String EIGHT_MONTH_AGO = "8个月前";
    private static final String NINE_MONTH_AGO = "9个月前";
    private static final String TEN_MONTH_AGO = "10个月前";
    private static final String ELEVEN_MONTH_AGO = "11个月前";
    private static final String ONE_YEAR_AGO = "一年前";



    public static String format(LocalDateTime date) {
        return format(localDateTimeToDate(date));
    }

    public static String format(Date date) {

        Calendar calendar = Calendar.getInstance();
        long now = calendar.getTimeInMillis();
        long delta = now - date.getTime();

        // 逻辑判断
        if (delta < ONE_MINUTE){  return delta/ONE_MILLISECOND + ONE_SECOND_AGO;}
        if (delta < ONE_HOUR){  return delta/ONE_MINUTE + ONE_MINUTE_AGO;}
        if (delta < ONE_DAY){  return delta/ONE_HOUR + ONE_HOUR_AGO;}
        if (delta < getTime(calendar, now)){ return delta/ONE_DAY + ONE_DAY_AGO;}
        if (delta < getTime(calendar, now)){ return ONE_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return TWO_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return THREE_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return FOUR_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return FIVE_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return SIX_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return SEVEN_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return EIGHT_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return NINE_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return TEN_MONTH_AGO;}
        if (delta < getTime(calendar, now)){ return ELEVEN_MONTH_AGO;}
        return ONE_YEAR_AGO;
    }

    private static long getTime(Calendar calendar, long now) {
        calendar.add(Calendar.MONTH, -1);
        return now - calendar.getTimeInMillis();
    }


    /**
     * LocalDateTime 转 Date
     * @param localDateTime
     * @return
     */
    public static Date localDateTimeToDate(LocalDateTime localDateTime){
        ZoneId zoneId = ZoneId.systemDefault();
        ZonedDateTime zdt = localDateTime.atZone(zoneId);
        return Date.from(zdt.toInstant());
    }

    /**
     * Date 转 LocalDateTime
     * @param date
     * @return
     */
    public static LocalDateTime dateToLocalDateTime(Date date){
        LocalDateTime localDateTime = date.toInstant()
                .atZone(ZoneId.systemDefault())
                .toLocalDateTime();
        return localDateTime;
    }
}